Quantitative histologic studies on the anterior pituitaries of various strains of guinea pigs

Abstract

Department of Agriculture has studied the effects of close inbreeding in the guinea pig. Twenty-four families were started and continued by brother to sister matings. Five of these families were maintained until 1933, but since then only families 2, 13, and 35, and certain crosscs betwcen thcse, remain. I n 1911 a control stock B was set up f o r comparison with the inbred lines. This control stock has been maintained by matings between animals which wcre no morc closely rclated than third cousins. Both the inbred and control animals have been maintained under identical conditions at the experimentaI farm of the U. S. Departmcnt of Agriculture at Beltsville, Maryland. During this long period of obscrvation differences in growth rate, fertility, mortality, color markings and other characteristics among various inbred lines, and between them and thc control stock have been noted, with thc differences in growth being the most marked. In the inbred families there has been a markcd reduction in fertility and a considerable reduction in growth rate. Prenatal and postnatal mortality have increased mrkcdly. That these declines in vigor wcre due in Considerable dcgrce to environmental condi-'Those studies were aided by a grant made t o Vwderbilt University by the Division of Medical Scienees of the Rockefcllcr Foundation.

Colloid in the pituitary pars distalis of viscacha (Lagostomus maximus maximus): Ultrastructure and occurrence in relation to season, sex, and growth

“…In rats (Wolfe, 1943), cattle (Bassett, 1951) and bat (Anthony and Gustafson, 1984), colloid is a conspicuous component of adult pituitary glands. Colloidal accumulations are rare and reduced in size in immature hamsters, guinea pigs, hedgehogs, and porcine, but these structures are larger and more numerous in older animals (Wolfe and Eaton, 1940;Shanklin, 1948;Hanke and Charipper, 1948;Spagnoli and Charipper, 1955;Curé et al, 1971;Kameda, 1990Kameda, , 1991Ogawa et al, 1996Ogawa et al, , 1997. The results obtained in pars distalis of viscacha suggest that the follicle formation was closely related to the body weight.…”

“…These results indicate that the effect of female reproductive activity on pituitary colloid may vary considerably from species to species. Some authors have also reported sex-related differences in the amount of pituitary colloid in guinea pigs (Wolfe and Eaton, 1940), and in hamsters and hedgehogs (Curé et al, 1971). In the present study, statistical comparisons between males and females of similar body weights showed that the seasonal changes of pituitary colloid in viscacha demonstrate a sexual dimorphism.…”

Occurrence of colloid‐containing follicles and ciliated cysts in the hypophysial pars tuberalis from guinea pigs of various ages

“…The number of follicles was greater in males than in females in each age group except the 5-day-olds. The sex difference in follicle number may be partly related to the fact that in guinea pigs the body weight and pituitary weight of males were heavier than those of females (Wolfe and Eaton, 1940). It is considered that the volume of pars tuberalis is larger in males than in females, resulting in greater numbers of follicles in male pars tuberalis.…”

A quantitative study of pituitary colloid in the batMyotis lucifugus lucifugusin relation to age, sex, and season

“…In rats (Wolfe, 19431, cattle (Bassett, 19511, and viscachas (Patil, 1976), colloid is a conspicuous component of adult pituitary glands, but none is evident in immature individuals at the light microscopic level. Colloid accumulations are rare and reduced in size in immature hamsters, guinea pigs, and hedgehogs; but these structures are larger and more numerous in older individuals (Wolfe and Eaton, 1940;Hanke and Charipper, 1948;Spagnoli and Charipper, 1955;Cure et al, 1971). Similarly, in humans, "follicular concretions" (which resemble somewhat the colloid accumulations described in other species) are more frequently observed in individuals over 40 than in younger individuals (Shanklin, 1948).…”

“…Various theories have, however, been proposed over the years regarding the mode of formation of colloid. Repeated observations of cell fragments within the colloid of the anterior lobe and hypophysial cleft have led numerous investigators to suggest that this substance arises as a byproduct of ceIIular degeneration (Wolfe and Eaton, 1940;Wolfe, 1943;Selye, 1943;Ferrer, 1956;Horvath et al, 1974;Ciocca and Gonzalez, 1978). An alternative hypothesis suggests that colloid is derived, at least in part, from interstitial fluids of the pars distalis (Ferrer, 1956;Vila-Porcile, 1972;Correr and Motta, 1981).…”